Honeycomb regenerator

Abstract

A honeycomb regenerator is constructed by (a) honeycomb structural bodies arranged in a high temperature portion, in which a temperature is over 1250° C. during a normal operation, made of aluminum-titanate or a combination of aluminum-titanate and mullite, and (b) honeycomb structural bodies arranged in a low temperature portion, made of cordierite and/or mullite, or by (a) honeycomb structural bodies arranged in a high temperature portion, to which an exhaust gas having a high temperature is contacted, made of aluminum-titanate or a combination of aluminum-titanate and mullite, (b) honeycomb structural bodies arranged in a middle temperature portion made of alumina and (c) honeycomb structural bodies arranged in a low temperature portion made of one material or a combination of materials selected from a group of cordierite, mullite and a porcelain. The honeycomb regenerator according to the invention can perform a heat exchanging operation effectively even in an exhaust gas having a high temperature and also in an exhaust gas having a high temperature and a corrosive property.

What is claimed is:  
     
       1. A honeycomb regenerator for recovering waste heat in an exhaust gas by passing an exhaust gas and a gas to be heated alternately therethrough, said honeycomb structural regenerator, comprising: 
       first honeycomb structural bodies comprising aluminum-titanate as a main crystal phase or a combination of aluminum-titanate and mullite and being stable at a temperature of at least 1250° C.; and  
       second honeycomb structural bodies, arranged adjacent said first honeycomb structural bodies in a direction parallel to a gas passing direction, comprising cordierite and/or mullite as a main crystal phase.  
     
     
       2. The honeycomb regenerator according to claim  1 , wherein the size of said first honeycomb structural bodies along a perimeter portion thereof is smaller than the size of said first honeycomb structural bodies arranged at a center portion residing within the perimeter portion. 
     
     
       3. The honeycomb regenerator according to claim  1 , wherein MgO and Fe 2 O 3  are added in said aluminum-titanate. 
     
     
       4. A honeycomb regenerator for recovering waste heat in an exhaust gas by passing an exhaust gas and a gas to be heated alternately therethrough, said honeycomb structural regenerator, comprising: 
       first honeycomb structural bodies arranged in a first portion and comprising aluminum-titanate as a main crystal phase or a combination of aluminum-titanate and mullite;  
       second honeycomb structural bodies, arranged in a second portion adjacent said first honeycomb structural bodies in a direction parallel to a gas passing direction, comprising alumina as a main crystal phase and being stable at a temperature of at least 1250° C.; and  
       third honeycomb structural bodies, arranged in a third portion adjacent said second honeycomb structural bodies in a direction parallel to a gas passing direction, comprising at least one material selected from the group consisting of cordierite, mullite and a porcelain having a corrosion resistivity.  
     
     
       5. The honeycomb regenerator according to claim  4 , wherein said first honeycomb structural bodies comprise aluminum-titanate as a main crystal phase, said second honeycomb structural bodies comprise alumina as a main crystal phase, and said third honeycomb structural bodies comprise cordierite as a main crystal phase. 
     
     
       6. The honeycomb regenerator according to claim  4 , wherein said aluminum-titanate includes 4˜10 wt % of MgO and 2˜10 wt % of Fe 2 O 3 . 
     
     
       7. The honeycomb regenerator according to claim  6 , wherein a thermal expansion coefficient of said first honeycomb structural bodies comprising aluminum-titanate as a main crystal phase or a combination of aluminum-titanate and mullite is under 1.0×10 −6 /° C. in a temperature range of 40˜800° C. 
     
     
       8. The honeycomb regenerator according to claim  4 , wherein said third honeycomb structural bodies comprise porcelain honeycomb structural bodies located at a position wherein, when exhaust gas is passing therethrouqh, a temperature is under a dew point of an acid included in said exhaust gas. 
     
     
       9. The honeycomb regenerator according to claim  4 , wherein a dimension of said first honeycomb structural bodies along a perimeter portion to which an exhaust gas having a high temperature may be contacted is smaller than that of said first honeycomb structural bodies arranged at a center portion.